A variety of insulative containers have been used to hold hot drinks and hot foods. A typical container is made from polystyrene, such as the cups used to hold coffee or microwavable foodstuffs.
Other containers have dual walled constructions in which an inner container is attached to an outer container to create an intermediate air gap. Still other containers use either an internal or external shell having longitudinal ribs that trap numerous independent air pockets between the ribs and the adjacent container. Those air pockets help insulate the contents of the container from the cooler temperatures of the surrounding air.
The polystyrene containers are problematic because they are not biodegradable. Therefore, many cup manufacturers, suppliers, and users have tried to be more environmentally conscious in choosing materials, such as paperboard. However, conventional paperboard containers, e.g., cups, have not had the insulating qualities of polystyrene. Attempts have been made to create usable dual walled cups made out of various materials, but those containers have proven to be less desirable due to poor insulating qualities or expense of manufacture. Consequently, there is a need for a new style of insulating container able to sufficiently limit the dissipation of heat from its contents, while being relatively inexpensive to manufacture and therefore competitive with traditional polystyrene cups and containers.